Paul Manafort speaks to reporters on the floor of the Republican National Convention at Quicken Loans Arena in Cleveland on July 17. Manafort this week turned over hundreds of pages of documents related to Russia to House and Senate intelligence committees. (Matt Rourke/AP)

President Trump’s former campaign chairman, Paul Manafort, turned over 305 pages of documents related to the investigation of Russian meddling in the 2016 election to the House and Senate intelligence committees this week, according to people familiar with the ongoing inquiries.

Manafort’s submission came in response to letters the congressional panels sent in recent weeks to a handful of Trump campaign associates with potential ties to Moscow, a sign that lawmakers were starting to dig deeper for details as newly appointed special counsel Robert S. Mueller III assumes leadership of a separate Justice Department inquiry.

Congressional staff have not fully reviewed the new Manafort documents, but people familiar with them said they include calendar entries, speech drafts and campaign strategy memos that mention Russia or individuals from Russia. They also cite some specific meetings, including two large group sessions that involved Russia’s ambassador to the United States — one at the Republican National Convention and the other at the Mayflower Hotel in Washington when Trump gave his first major foreign policy address.

A spokesman for Manafort, Jason Maloni, declined to provide any details on what Manafort provided to lawmakers but said the submission illustrated Manafort’s willingness to work with Congress on the matter.

“This is just another sign that he is following through on his commitment to cooperate with investigators,” Maloni said.

Team Trump’s ties to Russian interests

Officials from the two committees declined to comment.

As Trump’s campaign chairman during several key months in 2016, Manafort was tasked with managing the chaotic effort as the New York businessman shifted from being a Republican outsider to taking control of the party apparatus as its presidential nominee. He left the campaign in August after a tumultuous period during which documents surfaced suggesting he had received off-the-books payments from a Ukrainian political party. Manafort denied receiving improper payments.

Manafort once did business with a well-known Russian oligarch, Oleg Deripaska. Most of Manafort’s financial dealings were with Ukrainian officials and business leaders.

As a result, there were few personal business details included in the response, one person familiar with the documents said.

The Senate letter to Manafort requested information about contacts with Russian government and business figures, according to people familiar with the request.

Manafort’s response became public one day after former CIA director John Brennan told the House Intelligence Committee about the extent of Russian interference.

“It should be clear to everyone that Russia brazenly interfered in our 2016 presidential election process,” Brennan said at the hearing. Trump has refused to fully accept the unanimous conclusion of U.S. intelligence agencies that Russia stole thousands of sensitive emails, orchestrated online dumps of damaging information and employed “fake news” and other means to upend the 2016 race.

Similar letters were sent to Michael Flynn, who resigned as White House national security adviser, and Carter Page, who served briefly in the Trump campaign as a foreign policy adviser.

Flynn’s lawyers have said he will not provide the Senate with documents requested by subpoena saying Flynn plans to invoke his Fifth Amendment right against self-incrimination.

Federal inquiries have focused for some time on Page, who was the subject of a secret warrant last year issued by the Foreign Intelligence Surveillance Court, based on suspicion he may have been acting as an agent of the Russian government. Page has denied all wrongdoing and has said he plans to cooperate with the inquiries.